Puzzling Mice – City mice are better problem solvers

Featured Image Caption: Striped field mice have concurred the challenges of living in both city and country habitats (Image Source: “Brandmaus (Apodemus agrarius) im Körnerpark” by UsualRedAnt is licensed under CC BY-NC 2.0).

Reference: Mazza, V. & Guenther, A. (2020). City mice and country mice: Innovative problem solving in rural and urban noncommensal rodents. Animal Behaviour, 172, 197-210. https://doi.org/10.1016/j.anbehav.2020.12.007

It’s Not All Fun and Games

Games are a fun and engaging way to pass the time. Whether you like video games, card games, board games, athletic games, or puzzles, games stimulate our problem-solving brains and competitive spirit. We even like to watch people play games. Some of my favorite games to watch are obstacle courses where participants must jump, climb, bob, weave, run, balance, and most of all, strategize to complete the course in the shortest time. Obstacle courses require a great deal of problem-solving and critical thinking to master each obstacle.

Both city and county striped field mice face obstacles, but the environments they face are very different (Image Source: “Striped field mouse” by roxeteer is licensed under CC BY-NC-ND 2.0).

Animals also deal with obstacles in their environments. However, the stakes are much higher. Animals must find food, escape predators, build shelters, and locate a mate. These challenges can be even more difficult for animals that live in cities where human presence and constant change can further complicate matters. Using novel behaviors to solve problems is a favorable trait among urban animals. Those that can quickly solve problems are more likely to survive and reproduce. Mice, for example, can be extremely smart and innovative animals that have mastered both city and county environments.

But will urban and rural mice differ in their success and persistence in solving obstacles? When given eight obstacles to complete as quickly as possible, either city or county mice will emerge as the problem-solving victor.

Problem Solving Mice

The contestants of this obstacle challenge are striped field mice, Apodemus agrarius, from rural Uckermark and urban Berlin in Germany. Being a city or country mouse has its challenges. While food is difficult and infrequent to find for rural mice, city mice must learn to handle abundant but novel food sources. In cities, mice might have experience using human-made materials such as garbage and plastic, giving urban mice an advantage in this challenge. City mice must also deal with habitat loss, human disturbance, new predators, and all types of pollution. As mice cannot fly to escape from challenging circumstances, good problem-solving and innovative skills are crucial for survival in harsh environments.

Researchers collected striped field mice from the countryside of Uckermark and the city of Berlin in Germany (Image Sources: (left) “File:Locator map UM in Germany.svg” by TUBS is licensed under CC BY-SA 3.0, edited; (top) “Uckermark Landscape” by Jon Mountjoy is licensed under CC BY 2.0; (bottom) “File:Aerial view of Berlin (32881394137).jpg” by dronepicr is licensed under CC BY 2.0).

Researchers Dr. Valeria Mazza and Dr. Anja Guenther collected city and county mice and kept them in a lab for 12 months before testing their problem-solving wit with eight obstacles. First, the mice needed to learn the rules of each obstacle. The researchers gave the mice an open container with a food reward inside so that each mouse could explore the obstacle’s setup. After the mouse mastered the open container, the researchers put them to the test. They gave each mouse a similar closed container that required a motion to open and obtain the food. The first four obstacles could be solved using multiple different strategies (Check out this figure from the paper to see the setups!). The next three required a specific motion to open. In the final test, the mice needed to perform a sequence of actions to get to the food. The researchers recorded the time the mice spent approaching and interacting with the obstacles.

Success and Persistence
City mice spent less time gathering information and achieved greater success, which may be advantageous when facing the challenges of cities (Image Source: “Brandmaus Apodemus agrarius 180201 005.jpg” by juergen.mangelsdorf is licensed under CC BY-NC-ND 2.0).

City mice are the winners of these mouse puzzles, as they were more successful at solving all eight obstacles. Despite the city mice being better and faster at solving these obstacles, county mice were more persistent at solving the puzzle when they failed. Rural mice also approached the open and closed containers faster and spent more time interacting with the open container. In other words, city mice achieve success more quickly and spend less time gathering information, but country mice were determined to get the food no matter how long it took. These results suggest that striped field mice have adapted to novel and abundant food sources in cities and limited and varied food sources in the country.

Innovation helps city mice adjust to rapidly changing environments with novel resources. However, obtaining food quicker with less information may put city mice more at risk for eating poisonous food or being eaten themselves. In cities where food is abundant, it makes sense for mice to give up on a challenging obstacle to search for other food opportunities. Conversely, persistence is a favorable trait for mice in the country where food may be sporadic over space and time. If country mice don’t know where or when their next meal is coming, the best strategy is to take advantage of the current food opportunity. Cities are challenging habitats for many animals, but some have adapted to the rapid change by modifying behaviors and increasing innovative skills. As cities continue to grow and expand, we might expect to find more innovation from city animals.

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Brandi Pessman

I am a second-year Ph.D. student at the University of Nebraska-Lincoln in the School of Biological Sciences. Growing up on a farm in a small town in Illinois, I developed an early love for animals and a fascination with their behaviors. When I was younger, however, it never crossed my mind that I would be using spiders to investigate how human presence affects animal behavior, but I am loving every second of it. Studying the behaviors of animals can tell us a lot about the role that we play in their survival (or death), which is becoming increasingly important as human populations continue to grow. When I am not studying spiders, I enjoy playing with my cat or being outdoors!

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